Exhaust valve, exhaust valve assembly and exhaust valve system for two-stroke internal combustion engines, two-stroke internal combustion engine having same and method for cleaning an exhaust valve

Abstract

A two-stroke internal combustion engine has an engine block having a cylinder block and a cylinder head. The cylinder block defines a cylinder, an exhaust passage, and an exhaust valve passage. The engine also has a piston, an exhaust valve actuator operatively connected to at least one of the cylinder block and the cylinder head, and a reciprocating exhaust valve disposed at least in part in the exhaust valve passage. The exhaust valve has a shaft operatively connected to a valve actuator, and a blade connected to the shaft. A channel is defined along a face of the blade. The channel and a wall of the exhaust valve passage together define at least in part a valve passage. The valve passage permits flow of exhaust gas along the face of the blade. A width of the valve passage is at least a third of a width of the blade.

What is claimed is: 
     
       1. A two-stroke internal combustion engine comprising:
 an engine block having a cylinder block and a cylinder head, 
 the cylinder block defining:
 a cylinder defining a cylinder axis; 
 an exhaust passage communicating with the cylinder; and 
 an exhaust valve passage communicating with the exhaust passage, the exhaust valve passage having a first wall and a second wall; 
 
 the cylinder head being connected to the cylinder block, the first wall of the exhaust valve passage being closer to the cylinder head than the second wall of the exhaust valve passage in a direction defined by the cylinder axis; 
 a piston disposed in the cylinder; 
 an exhaust valve actuator operatively connected to at least one of the cylinder block and the cylinder head; and 
 a reciprocating exhaust valve disposed at least in part in the exhaust valve passage, the reciprocating exhaust valve comprising:
 a shaft operatively connected to a valve actuator, the shaft defining a reciprocation axis of the valve, the reciprocation axis defining a longitudinal direction of the valve; and 
 a blade having:
 a first end having an arcuate edge; 
 a second end opposite the first end, the shaft being connected to the second end; 
 a first face facing the first wall of the exhaust valve passage; and 
 a second face opposite the first face, the second face facing the second wall of the exhaust valve passage, 
 each of the first and second faces extending between the first and second ends, 
 a channel being defined along the second face, the channel extending in the longitudinal direction from the first end to the second end; 
 
 
 the channel and the second wall of the exhaust valve passage together defining at least in part a valve passage, the valve passage permitting flow of exhaust gas from the first end of the blade to the second end of the blade, 
 a width of the valve passage being at least a third of a width of the blade, the width of the valve passage and the width of the blade being measured in a lateral direction, the lateral direction being perpendicular to the longitudinal direction. 
 
     
     
       2. The two-stroke internal combustion engine of  claim 1 , wherein the width of the valve passage being at least half of the width of the blade. 
     
     
       3. The two-stroke internal combustion engine of  claim 1 , wherein:
 the channel is a first channel; 
 a second channel is defined along the second face, the second channel extends in the longitudinal direction from the first end to the second end; 
 the first and second channels are disposed on opposite sides of the reciprocation axis; and 
 the valve passage is defined at least in part by the first channel, the second channel and the second wall of the exhaust valve passage. 
 
     
     
       4. The two-stroke internal combustion engine of  claim 1 , wherein a majority of the first face is flat. 
     
     
       5. The two-stroke internal combustion engine of  claim 1 , wherein:
 the blade has:
 a first end portion adjacent the first end; 
 a second end portion adjacent the second end; and 
 a mid-portion disposed longitudinally between the first and second end portions; 
 
 a thickness of a part of the second end portion defining the channel being less than a thickness of a part of the mid-portion defining the channel, the thickness of the part of the second end portion and of the part of the mid-portion being measured in a direction perpendicular to the longitudinal and lateral directions. 
 
     
     
       6. The two-stroke internal combustion engine of  claim 1 , wherein the shaft defines a stopper. 
     
     
       7. The two-stroke internal combustion engine of  claim 6 , wherein the stopper being in sliding fit with the exhaust valve passage. 
     
     
       8. The two-stroke internal combustion engine of  claim 7 , wherein a clearance between the stopper and a portion of the cylinder block defining the exhaust valve passage is less than a minimum clearance between the blade and the portion of the cylinder block defining the exhaust valve passage. 
     
     
       9. The two-stoke internal combustion engine of  claim 6 , wherein a maximum thickness of the valve passage is at least one third of a diameter of the stopper, the thickness of the valve passage being measured in a direction perpendicular to the longitudinal and lateral directions. 
     
     
       10. The two-stroke internal combustion engine of  claim 1 , wherein;
 the cylinder is a plurality of cylinders; 
 the exhaust passage is a plurality of exhaust passages, each exhaust passage of the plurality of exhaust passages communicating with a corresponding cylinder of the plurality of cylinders; 
 the exhaust valve passage is a plurality of exhaust valve passages, each exhaust valve passage of the plurality of exhaust valve passages communicating with a corresponding exhaust passage of the plurality of exhaust passages; 
 the piston is a plurality of pistons, each piston of the plurality of pistons is disposed in a corresponding cylinder of the plurality of cylinders; and 
 the reciprocating exhaust valve is a plurality of reciprocating exhaust valves, each reciprocating exhaust valve of the plurality of reciprocating exhaust valves being disposed at least in part in a corresponding exhaust valve passage of the plurality of exhaust valve passages. 
 
     
     
       11. The two-stroke internal combustion engine of  claim 10 , wherein each reciprocating exhaust valve of the plurality of reciprocating exhaust valves is operatively connected to the exhaust valve actuator.